Despite his sense of humor and easygoing conversational manner (especially around other accountants, like Ben Wyatt), his lectures and demonstrations of accounting software (QuickBooks Pro ) are tediously boring; cheerfully delivered in a monotone voice and interspersed with awkward puns related to accounting. Invariably, Andy Dwyer is the only person who finds Barney's wordplay entertaining.
Eager to please, he has offered Ben Wyatt a position at his firm on multiple occasions, but was declined each time–though this has not created tension between them. Ben's propensity for reciting his own accounting puns always results in raucous laughter from Barney, who will usually call in Ted (an unseen employee at the firm) to hear Ben's joke.
He first appears in the episode "Leslie's House", when he bursts in, demanding that his class be evaluated. During his presentation, he makes several accounting puns: "The only thing that's taxing is deciding what software to buy", "When it comes to accounting software, there's no accounting for taste" as well as "...and that concludes a quick look at QuickBooks Pro". He appears again in Telethon giving the same presentation he did at Leslie's party as apart of the Telethon.
Ben Wyatt applied for a job with Barney's accounting firm in Season 4. Ben was talked out of the job by Jean-Ralphio, who then applied for the job himself, but Barney discovered Jean-Ralphio knew nothing about accounting and immediately fired him after sexually harassing one of firm's female employees.
In "The Cones of Dunshire", Ben Wyatt applies for a job at Barney's accounting firm again after being fired from Sweetums. Barney excitedly shakes hands with Ben, and runs to his coworker, Ted, while shouting, "Ted, he's here! He really came!" Barney is extremely ecstatic that Ben returns and consistently praises him for his work, going as far as throwing a small party that includes Ben's favorite food, calzones. At the end of the episode, however, Ben once again quits his job because he was offered the job as Pawnee's city manager. Barney is disappointed but understands, and he is pleased with Ben's parting gift of the "Cones of Dunshire" game prototype.
Barney later attends the grand opening of Tom's Bistro, where he reveals to Ben that he and the other accountants had patented "The Cones of Dunshire" in Ben's name. He presents the patent as a gift to Ben, who was so pleased that he agrees to come work at the accounting firm (though he recants almost immediately).